Fidelity to foraging sites, consistency of migration routes and habitat modulation of home range by sea turtles

Aim  Resources can shape patterns of habitat utilization. Recently a broad foraging dichotomy between oceanic and coastal sites has been revealed for loggerhead sea turtles (Caretta caretta). Since oceanic and coastal foraging sites differ in prey availability, we might expect a gross difference in home-range size across these habitats. We tested this hypothesis by equipping nine adult male loggerhead sea turtles with GPS tracking devices. Location  National Marine Park of Zakynthos (NMPZ) Greece, central and eastern Mediterranean (Adriatic, Ionian and Aegean seas). Methods  In 2007, 2008 and 2009, Fastloc GPS-Argos transmitters were attached to nine male loggerheads. In addition, a Sirtrack PTT unit was attached to one male in 2007. Four of the turtles were tracked on successive years. We filtered the GPS data to ensure comparable data volumes. Route consistency between breeding and foraging sites of the four re-tracked turtles was conducted. Foraging site home range areas and within site movement patterns were investigated by the fixed kernel density method. Results  Foraging home range size ranged between circa 10 km2 at neritic habitats (coastal and open-sea on the continental shelf) to circa 1000 km2 at oceanic sites (using 90% kernel estimates), the latter most probably reflecting sparsely distributed oceanic prey. Across different years individuals did not follow exactly the same migration routes, but did show fidelity to their previous foraging sites, whether oceanic or neritic, with accurate homing in the final stages of migration. Main conclusions  The broad distribution and diverse life-history strategies of this population could complicate the identification of priority marine protected areas beyond the core breeding site.

Conservation hotspots : implications of intense spatial area use by breeding male and female loggerheads at the Mediterranean’s largest rookery

The implementation of appropriate protection measures for endangered species in protected areas requires knowledge of their fine-scale habitat use. In May and June of 2006 and 2007, we used GPS loggers (some linked to the Argos system) and a conventional Argos transmitter to track male and female loggerhead turtles Caretta caretta in the vicinity of the breeding area of Laganas Bay within the National Marine Park of Zakynthos, Greece. We obtained (1) 9681 useable locations (mean: 1383 locations ind.–1; range: 519 to 2198 locations) from Tracktag GPS loggers attached to 7 females for a mean duration of 34 d (range: 17 to 52 d); (2) 1245 useable locations (mean: 311 locations ind.–1; range: 38 to 1110 locations) from 4 males fitted with Fastloc Argos tags for a mean duration of 29 d (range: 3 to 51 d) and (3) 100 locations from 1 male fitted with a conventional Argos satellite tag tracked for 128 d. GPS data indicated that before the onset of nesting, both males and females primarily used an area within 500 m of the shore along a core 9 km stretch of coastline, where existing protective legislation requires strengthening. Our observations suggest that a 76.7% female-biased operational sex ratio, measured previously from in-water surveys, may represent a realistic sex ratio estimate in the period before nesting starts. In the first month following the onset of nesting, female spatial distribution remained similar, whereas most males departed for distant areas presumably to forage. Our study provides quantitative evidence of the need to improve the management planning and conservation measures to protect sea turtles in a coastal breeding area, and new insights on male turtle migration.

Gender congruity and social processes of leadership: is gender balance important?

This article presents the results of a study investigating the effects of gender balance on leadership processes at a workgroup and industry level. Leadership is conceptualized as a social process occurring between individuals, rather than as the behavior or attribute of a single individual. Transformational leadership processes were found less often in male-dominated industries. Furthermore, gender congruity effects were found, showing that gender balance between work teams and industries affects leadership processes between individuals. Leadership processes were reported most often in female-dominated work teams within female-dominated industries, but least often in female-dominated work teams within male-dominated industries. The implications for both leadership and gender research are discussed.

Foraging behaviour of two rodent species inhabiting a kopje (rocky outcrop) in Tsavo West National Park, Kenya

We employed patch use theory to evaluate how several environmental factors influence the foraging behaviour of two rodent species: Grammomys dolichurus and Acomys cahirinus. Foraging efficiency was determined by measuring the remaining food in artificial food patches (giving-up densities: GUDs) from two experiments. In the first experiment, we placed patches in different microhabitat types (cover vs open) and at varying distances from cover. This experiment was conducted during three moon stages (waxing, full, waning). We found that the rodents had higher GUDs (lower foraging efficiency) in the open microhabitat. The distance from nearest shelter had a marginally significant positive effect on GUDs. GUDs were higher in both microhabitat types during the waxing and full phases, but decreased sharply once the moon began to rise after sunset. These results are likely due to higher predation risk away from cover and in more illuminated environments. In the second experiment, we examined mouse responses to seeds impregnated with plant toxins. Seeds impregnated with oxalic acid were avoided by the rodents, while seeds soaked in tannic acid did not differ significantly from control seeds. Our results highlight important ecological factors affecting the foraging behaviour of these rodents.

A preliminary study of bryophytes and invertebrates of soil crusts in the Little Desert National Park and surrounds

This study is preliminary to ongoing investigations of soil crusts and associated invertebrates in north-west Victoria, focusing on the Little Desert National Park. Ninety quadrats from nine sites were sampled. Eighteen bryophyte species (nine mosses, nine liverworts) were identified within the quadrats. All invertebrates were from the Phylum Arthropoda. Overall abundance and diversity of invertebrates was low. While sampling in the drier months is valuable for observing the dynamics of soil crusts in this region, a more comprehensive assessment of species diversity is gained by sampling
during wetter periods.

Population structure and life history characteristics of euastacus bispinosus and cherax destructor (Parastacidae) in the Grampians National Park, Australia

Despite being the most widely distributed and cultured freshwater crayfish species in Australia, relatively little is known about the ecology of Cherax destructor outside of captivity. Similarly, few ecological studies have been conducted on the large and threatened stream dwelling Australian freshwater crayfish Euastacus bispinosus. A series of seasonal sampling surveys over two years investigated the population structure, life history and reproductive timing of C. destructor in fire dam habitats, and of E. bispinosus in channel (stream) habitats, in the Grampians National Park in south-west Victoria, Australia. Cherax destructor individuals in the largest size class (50 – 59.95 mm OCL) were not abundant during the study, while those belonging to the 0 – 9.95 mm OCL size class were more frequent in summer than at other times of year, suggesting synchronous recruitment in fire dam habitats. Individuals in the reproductively active mid-size classes were also frequent in summer. For E. bispinosus, sex ratios in spring always favoured females, although there were no clear trends for other times of year. Gravid E. bispinosus females were found in winter and spring throughout the study, and were sexually mature at a smaller size than has previously been reported.

Distribution of disease caused by Phytophthora cinnamomi in Wilsons Promontory National Park and potential for further impact

The extent of disease caused by Phytophthora cinnamomi was determined within vegetation communities of Wilsons Promontory National Park. Aerial survey of visible symptoms by helicopter and systematic survey along all roads and tracks followed by isolation of the pathogen from soil found that in total 551 ha of moist foothill forest, heath and heathy woodland broad vegetation types were affected by the disease. P. cinnamomi was isolated from 93% of sites that, based on the presence of visible symptoms, were expected to yield the pathogen. The species-rich heathy woodland was most affected with 6.5% of the total area of this type showing symptoms of disease. The size of infestation ranged from 229 ha on the slopes of the Vereker Range in the north to less than 1 ha along the Sealers Cove Walking Track in the south. The potential for disease to spread into uninfested vegetation was estimated for all sites from which P. cinnamomi was isolated. Eight of 18 sites where evidence of disease was found were estimated to have a high potential for further disease spread. This study indicates that even though the disease may be waning in some areas of the Park, the pathogen is active and easily isolated from others and provides a continuing threat to susceptible vegetation communities.

Investigating the distribution of acacia longifolia ssp. sophorae in south-west Victoria using satellite remote sensing and GIS

Mapping and analysis of the distribution of environmental weeds is an important component of strategic weed management. Such information is particularly important in managing 'native invaders', where invasion characteristics must be clearly understood prior to any management action being taken. This paper reports on an investigation of the current distribution of the native invader Acacia longifolia ssp. sophorae (Labill.) Court (coast wattle) in south-west Victoria, using remote sensing and Geographic Information Systems (GIS). Coast wattle was successfully mapped from Landsat ETM imagery using a supervised classification procedure, with 82%, of coast wattle shown on the map accurately depicting coast wattle on the ground. An estimated 11,448 ha were classified as supporting coast wattle, representing 12% of native vegetation in the study area. A more detailed GIS analysis in the Lower Glenelg National Park revealed coast wattle has invaded a limited number of vegetation types, and is more prevalent close to roads and within management zones associated with disturbance. The current regional extent of the species means widespread control is unlikely; hence the immediate focus should be on preventing further spread into areas where it is currently absent. Landsat imagery also proved to be a successful tool for mapping large scale coast wattle distribution, and could be used in long-term monitoring of the species.

Estimating the economic value of Mount Buffalo National Park with the travel cost and contingent valuation models

The Mount Buffalo National Park is the oldest national park in Victoria, Australia. There has been a rapid increase in the number of visitors to the park during the last decade and park management has been a concern, especially in the light of declining budgetary allocations and potential damage due to the increased visitor numbers. Policy options to increase park revenue remain unclear because of a lack of information on demand parameters and user costs. This study estimates the economic value of the park using the travel cost method (TCM) and the contingent valuation method (CVM). The TCM gives higher consumer surplus (CS) than the CVM. The CS shows that the economic value of the park is high and that there are opportunities to introduce innovative fee schemes to enhance its revenue. Present entry fee systems do not capture the economic value of the park.

Further Observations on the Diet of the Sooty Owl Tyto Tenebricosa in the Royal National Park, Sydney

Dietary samples from four Sooty Owl Tyto tenebricosa roost-sites within one territory in the Royal National Park, Sydney, New South Wales, were collected in December 2005. A total of 144 dietary items was identified, representing eight mammal species and at least one bird species. The samples were compared with those collected during a study 10 years earlier (in 1994-96) that included samples from the same roost-sites. Ten years later, the diet of the Sooty Owl in this territory appears little changed, except that the Sugar Glider Petaurus breviceps is now taken more frequently. The Common Ringtail Possum Pseudocheirus peregrinus continued to be the principal prey species taken by the Owls at this location. The Long-nosed Bandicoot Perameles nasuta may have declined in the Sooty Owl's diet during this period, but this trend was not significant statistically. This study showed that Sooty Owl diet at a single location is relatively stable, despite the occurrence of a major disturbance to habitat caused by a severe wildfire 12 years previously.

Range extension of the Millewa Skink Hemiergis millewae in the Murray-Sunset National Park, Victoria

This article reports a range extension for the critically endangered Millewa Skink Hemiergis millewae in Victoria. An individual H. millewae was found approximately 85 km east of its former known range in mature mallee vegetation, near the eastern edge of the Murray-Sunset National Park on 27 March 2007. Site characteristics are described, and a list of other reptile species found at the same site is provided. Further research into the habitat associations and distribution of H. millewae is recommended in order to guide the management of this species.